Despite the cataclysmic volcanic flood basalt outpourings 17 millions years ago beautiful Columbia River Gorge set the stage for up to 90 catastrophic events that happened between 15.000 and 13.000 years ago. At that time the ice age was about to come to an end. The large ice sheet over British Columbia advanced into the mountainous terrain of northern Idaho and northeastern Washington slowly filling the Columbia Basin between the Cascade Range and the Rocky Mountains. The advancing ice blocked the Clark Fork River that drained the ice sheet and numerous glaciers in the Rockies. Consequently meltwater backed up into the valleys of northwestern Montana building up a huge lake known as Glacial Lake Missoula. The water reached a depth of about 2000 ft (600 m) where the ice blocked the canyon on a length of 30 miles (50 km). At that time the ice dam began to float opening tunnels for the draining meltwater within hours. Finally the ice dam collapsed resulting in a torrential flood that cut back the canyon walls of the Columbia River Gorge. Rivers flowing into the gorge were left hanging resulting in today’s beautiful waterfalls.
August 2008
Canon 20D, Canon EF-S 10-22mm, f/22, 2 sec, ISO 100, tripod